Hum figured i could come out of lurking for this one.
In this chapter they main character is fighting a monster that can steal powers. When it steals its powers it can also take on owners appearance.
The full manga can be found at
http://www.mediafire.com/?ffrntt3iggw
He also changes into other girls near the end of the chapter.
Forgot to mention, I can't wait for the anime to air this scene.